getting rid of all but certain headers

I'm a little tired of some of the gross excesses I'm seeing in headers, some  
X-Headers, some non-X-headers that should be X-Headers.

Is there a way to have procmail/formail strip all but a certain set of  
headers that I would define somewhere?

Yes there are places where this shouldn't be done, etc etc etc etc.  I  
realize all of that.

I'm still curious how I would do it if I were to do it.

Thanks

TjL